Be careful to split with regular expressions - character set and locale issues:

<pre><?php
setlocale( LC_ALL, 'nb_NO.utf8');
var_dump( preg_split( '/\W/u', 'blårbærøl er greit' ) );
?>
Output
array(3) {
  [0]=>
  string(12) "blårbærøl"
  [1]=>
  string(2) "er"
  [2]=>
  string(5) "greit"
}